Schedule Of Significant Deferred Tax Assets And Liabilities (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Schedule of Deferred Income Tax Assets and Liabilities [Line Items]
Receivables allowance	$ 1,026	$ 456
Inventory	234	177
Asset retirement obligation	530	492
Accrued liabilities	10,177	8,695
Operating loss carryforward	21,254	32,946
Goodwill and intangibles	5,119	8,298
Deferred compensation	7,851	6,732
Total deferred tax assets	46,191	57,796
Property and equipment	(199,765)	(199,795)
Prepaid expenses	(2,414)	(2,398)
Total deferred tax liabilities	(202,179)	(202,193)
Net deferred tax liability	(155,988)	(144,397)
Deferred tax assets - current	29,113	39,154
Deferred tax liabilities - non-current	(185,101)	(183,551)
Net deferred tax liability	$ (155,988)	$ (144,397)